1. Technical Field
The present invention relates to a measurement apparatus, a parallel measurement apparatus, a test apparatus, and an electronic device.
2. Related Art
A known apparatus for sampling a signal under measurement according to a prescribed sampling signal operates by delaying the sampling signal with delay elements having different delay amounts to generate a plurality of strobe timings, as described in Patent Document 1, for example. In this case, by inputting the signal under measurement and different strobe timings into comparison circuits arranged in parallel, the signal under measurement can be sampled with a resolution corresponding to the delay amounts of the delay elements.    Patent Document 1: Japanese Patent Application Publication No. 2004-325332
In the above apparatus, however, a number of comparison circuits and delay elements corresponding to the resolution and the measurement range are provided. In other words, when performing measurement with a higher resolution over a wider measurement range, a larger number of comparison circuits and delay elements are provided. Therefore, when the size and power consumption of circuits are important, an apparatus with smaller circuits and lower power consumption is preferable.
Furthermore, in the above apparatus, the delay amounts of the delay elements correspond to the measurement resolution. Therefore, an apparatus is desired that can perform measurement with a higher resolution when measuring the signal under measurement with units of resolution that are less than the smallest delay time of the delay elements.
In the above apparatus, variation in the delay amounts of the delay elements affects the measurement accuracy. Therefore, an apparatus is desired that can perform highly accurate measurement when the delay amount variation among the delay elements is too large to be ignored.
In the above apparatus, in order for the delay elements to generate the prescribed delay amounts, it is necessary to detect in advance the setting values to be set in the delay elements to achieve the prescribed delay amounts. In this case, the delay amounts obtained for certain setting values can be measured by forming a loop that feeds the output of a delay element set with the prescribed setting values back to the input terminal of the delay element, and measuring the period of the loop oscillation. Then, by sequentially changing the setting values, the delay amount for each setting value can be measured. However, it is difficult for the measurement of the delay amount corresponding to each setting value to be performed simultaneously, and so measurement errors occur when there are power supply voltage variations or temperature variations between measurements for different setting values. Therefore, an apparatus with decreased measurement error is desired when the measurement error is too large to be ignored.